Heretofore a variety of designs have been proposed for sewage aeration systems comprising a header pipe, a holder, a porous diffusion element, means for retaining the diffusion element in the holder, sealing means and air flow regulator means. Examples may be found for instance in U.S. Pat. Nos. 2,346,367, 3,083,953, 3,532,272, 3,733,064, 3,970,731 and 4,007,240.
Experience with commercially available sewage aeration systems of the above mentioned type, as well as careful study and experimentation, have shown that such systems suffer from one or more shortcomings alone or in combination. Among these are tendencies to produce excessive quantities of large bubbles, with resultant impairment of oxygen transfer efficiency; expense and complexity of system components; complexity and labor costs associated with field installation; a certain tendency to cause breakage of diffusion elements during installation; lack of uniformity of distribution among diffusion elements; lack of uniformity in the distribution of air flow across individual diffusion elements; and other difficulties. The purpose of the present invention is to reduce or eliminate these difficulties and provide an improved sewage aeration system.